Efflux Time Research Articles

Effect of Changing the Concentration of Zinc Oxide Nanoparticles on the Viscosity of the Polyacrylamide / Polyethylene Glycol Solutions

In this work, Polyacrylamide/ Polyethylene glycol solutions of different molecular weights for Polyethylene glycol and different concentrations (17, 29, 38, 45, and 57 %) of ZnO nanoparticles were prepared by dissolving 0.5g of Polyethylene glycol in 20mL Polyacrylamide, then adding different concentrations of ZnO nanoparticles. Relative viscosity values are calculated by using the efflux time of the solutions, the viscosities(relative viscosity (ƞr), specific viscosity (ƞsp), reduced viscosity (ƞred) and inherent viscosity (ƞint) were calculated for all solutions, where measurements indicated an increase in these properties with increased concentration of ZnO nanoparticles and increased molecular weight of Polyethylene glycol. Viscosity is a significant parameter during the electrospinning process, and if the molecular weight increases, the viscosity of the solutions increases, making subsequent synthesis and purification more difficult. the constants KH and KK were calculated from the slopes of the viscosity values related to the Huggins and Kramer equations. These results can be used in many applications and scientific studies.

Enhanced impact properties of functionally graded preplaced aggregate fibrous concrete slabs comprising alkali-activated slag and carbon nanotube grout

Nowadays, cement manufacturing stands as the third most significant contributor to anthropogenic CO2 emissions. Alkali-activated techniques are emerging as a potentially more environmentally friendly alternate binder to mitigate the risks related to climate change. The current investigation utilizes the notion of preplaced aggregate concrete (PAC) and alkali-activated slag grouts comprising multi-walled carbon nanotubes (MWCNT) of 0.1 % dosage to implement functionally graded preplaced aggregate fibrous concrete slabs (FGPAFC). The optimum efflux time of alkali-activated slag grouts was determined through trials with various superplasticizer dosages and water-to-binder ratios. However, as it has not been investigated previously, the effect of alkali-activated grout made up of MWCNT on the impact strength of the FGPAFC slab deserves special focus. For this, seven different slabs were prepared, in which five three-layered FGPAFC slabs containing a steel fibre at a dosage of 3.5–4.5 % at a 0.25 % increment were provided at the upper and lower layers. At the same time, the middle layer contains 0–2 % fibres at 0.5 % increment. Using the same amount of fibre as in FGPAFC, a PAC slab with uniform fibre distribution is made to examine how effectively the three-layer arrangement performs. The slab underwent an impact test in accordance with the guidelines set forth by ACI Committee 544. The cracking and failure impact number, crack resistance at service and ultimate stages, impact ductility, the ratio of crack resistance, failure pattern, and its mechanism were examined. Findings reveal that the cracking and failure impact energies were enhanced by roughly 3–12 % and 15–53 %, respectively, by lowering the fibre content at the middle layer and raising it at the upper and lower layers of the FGPAFC slab from 3.0 progressively to 4.5 %. The contribution of steel fibre is more significant than MWCNT for enriching the impact resistance of FGPAFC. The findings derived from this study offer foundational data for subsequent comprehensive scientific examination of FPAFC subjected to impact.

Pumice and lapillus scraps: New national environmental-friendly chance for the production of ceramic tiles

Italian pumice and volcanic lapillus scraps have been used in different percentages as alternative raw materials to foreign feldspars in porcelain stoneware mixtures. The aim of this work was to create naturally colored support to limit the use of artificial dyes while maintaining the technical properties of the reference product. For this purpose, the significant presence of chromophores (Fe and Ti in particular) in by-products from extraction of Italian volcanic pumice and lapillus was exploited. The work was carried out in collaboration with a company: the products were made on a laboratory scale and then they were glazed and fired within the industrial production cycle (48 min, 1210 °C).The resulting slip and the fired samples were characterized by measuring the efflux time, density, linear shrinkage, water absorption and tensile strength to evaluate the technological performance. In addition, thermogravimetric analysis (TG), differential thermal analysis (DTA), and optical and mechanical dilatometry were performed to study the thermal behavior of the formulations.The obtained products could be classified as porcelain stoneware and belong to the BIa group (WA 0.5%, B.S.>35 MPa) in accordance with UNI EN 14411 ISO 13006.

Fresh state and hydration properties of high-volume lithium slag cement composites

In this study, the fresh state and hydration properties of 0–60% lithium slag blended cement pastes were investigated at water-binder ratio of 0.47. The workability of the fresh pastes was evaluated by measuring the air content, marsh cone flow, mini-slump flow, setting times, and through rheology tests. A 40% lithium slag cement could produce 91% strength activity index at 28 days; mini-slump pat diameter of 70.54 mm; marsh cone flow efflux time of 145 s; air content 0.6%; hydration heat of 300 J/g (at 72 h). At replacement levels above 40%, the strength activity index, air content, mini-slump flow, hydration heat, and fluidity were significantly reduced. Experimental investigations confirm that the mini-slump test provides the best correlation coefficients (R2 = 0.96) with the maximum shear viscosity of lithium slag cement pastes than the marsh cone flow efflux time and air content. The classical slump and rheological models were used to characterise the mini-slump, yield stress, and plastic viscosity of low to high volume lithium slag cement pastes. The present study recommends that a 40% lithium slag cement paste is a viable option to produce green concrete for optimum fresh, hydration, rheological, and hardened properties.

Effects of modified binders on flowability of grout and properties of preplaced aggregate concrete

In preplaced aggregate concrete (PAC), it is important yet complex to achieve a grout with high flowability and bleed resistance simultaneously. Supplementary cementitious materials, typically incorporated to impart desired properties to concrete and to complement economic and environmental benefits, may uniquely alter the properties of PAC to that of conventional concrete. Therefore, comprehensive knowledge of incorporating supplementary cementitious materials, considering alterations in their flowability and constituent materials to improve the overall performance of PAC is essential. The present study investigates the properties of PAC, incorporating ground granulated blast furnace slag (GGBS) and silica fume (SF) as partial replacement of cement at 0–40% and 0–10%, respectively. Different proportions of GGBS and SF were considered, where, flowability and superplasticizer dosage were varied with and without incorporating sand. Grout properties were evaluated in terms of flowability and compressive strength and PAC properties were evaluated in terms of mechanical strength, durability, and dimensional stability. The findings revealed that the combination of GGBS and SF in grout displayed suitable flowability and acceptable strength. Removal of sand from grout improved the properties of grout while deteriorating the properties of PAC. PAC produced using grout with 10% SF and sand to binder ratio of 0.5, exhibiting efflux time of less than 20 s, displayed the highest compressive strength. GGBS and SF significantly improved chloride ion penetration of PAC with the drawback of increased drying shrinkage. Nevertheless, all PAC mixes could still be classified as low shrinkage concrete. PAC produced with 40% GGBS and 10% SF exhibited comparable compressive strength and enhanced resistance to chloride ion penetration to that of PAC without GGBS/SF.

Optimization of the Injection and Physical Properties of Sulfoaluminate Cement via the In Situ Polymerization of Acrylamide

Deep coal mining requires grouting to reinforce the coal rock walls. The conventional polymer-modified cement-based grouting materials have improved toughness but poor fluidity. The purpose of this paper was to improve the injectability of grout. The preconditions were that the physical properties of the stones are not obviously damaged and the mechanical properties are optimized. The acrylamide monomer was incorporated into the sulfoaluminate cement-based grouting material system. The effects of the in situ polymerization modification of the acrylamide on the paste properties and stone body strength were investigated. The results showed that the acrylamide mixed with the sulfoaluminate cement could increase the fluidity of the grouting material, prolong the paste setting time, and improve the flexural strength of the stone body. Compared with the blank group, the 500 mL efflux time of the 1006 mud viscometer in the 35% AM (acrylamide) dosing group decreased from 51 s to 41 s, the initial setting time increased from 15 min to 98 min, and the flexural strength at three days increased by 202.8%. The compressive stress–strain of the stone body gradually changed from brittle to ductile damage as the acrylamide dosing increased. Based on the microscopic analysis, a composite structure model of the inorganic skeleton of the flexible polyacrylamide network of toughened AFt (ettringite) was built in this paper. A mechanical study of the compressive stress–strain characteristics of the stone body was performed. It was concluded that the acrylamide in situ polymerization-modified sulfoaluminate cement-based grouting material is suitable for coal rock wall grouting reinforcement.

Enzyme-mediated intratumoral self-assembly of nanotheranostics for enhanced imaging and tumor therapy.

Enzyme-mediated intratumoral self-assembled (EMISA) nanotheranostics represent a new class of smart agents for combined imaging and therapy of cancer. Cancer cells overexpress various enzymes that are essential for high metabolism, fast proliferation, and tissue invasion and metastasis. By conjugating small molecules that contain an enzyme-specific cleavage site to appropriate chemical linkers, it is possible to induce self-assembly of nanostructures in tumor cells having the target enzyme. This approach of injecting small theranostic molecules that eventually become larger nanotheranostics in situ avoids some of the major limitations that are encountered when injecting larger, pre-assembled nanotheranostics. The advantage of EMISA nanotheranostics include the avoidance of nonspecific uptake and rapid clearance by phagocytic cells, increased cellular accumulation, reduced drug efflux and prolonged cellular exposure time, all of which lead to an amplified imaging signal and therapeutic efficacy. We review here the different approaches that can be used for preparing EMISA-based organic, inorganic, or organic/inorganic hybrid nanotheranostics based on noncovalent interactions and/or covalent bonding. Imaging examples are shown for fluorescence imaging, nuclear imaging, photoacoustic imaging, Raman imaging, computed tomography imaging, bioluminescent imaging, and magnetic resonance imaging. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Biology-Inspired Nanomaterials > Peptide-Based Structures.

Efflux Time for Two Exit Pipe System

Based on integral balances, mathematical equation for efflux time during gravity draining of a Newtonian liquid (below its bubble point) from a large open cylindrical storage tank (Where the flow in the storage tank is essentially laminar) through two exit pipes of same diameter located at the bottom of the vessel (The flow is assumed to be turbulent in each of the exit pipes) is developed. The equation is ultimately simplified and written in dimensionless form. The equation will be of use for arriving at the minimum time required for draining the contents of a cylindrical storage vessel through two exit pipe. The equation is verified with the experi- mental data. A maximum deviation of 19% and an average deviation of 16% are observed. The effect of initial height of liquid on Reynolds' number is also established. It is shown that while draining a liquid from the cylindrical storage tank through exit pipe system, Froude number re- mains constant.

Comparison of Efflux Time between Cylindrical and Conical Tanks Through an Exit Pipe

Mathematical equations for efflux time during gravity draining of a Newtonian liquid (below its bubble point) from large open storage tanks of cylindrical and conical shapes (Where the flow in the respective tanks is essentially laminar) through an exit pipe of same length and cross sectional area (the flow in the exit pipe line being turbulent) located at the bottom of the respective storage tanks are developed. The equations are ultimately simplified and written in dimensionless forms. These equations will be of use in arriving at the minimum time required for draining the contents of the respective geometries of storage vessels. To drain the same volume of liquid, the efflux time equations so developed are compared to find out which of the tanks considered drain faster.

Development of sustainable alkali-activated slag grout for preplaced aggregate concrete

Cement production is currently the third largest source of CO2 anthropogenic emissions. To mitigate the associated climate change threats, alkali-activated systems have emerged as a promising cleaner alternative binder. The present study deploys orthogonal experimental design and ANOVA analysis to develop alkali-activated slag (AAS) grouts with adequate fresh and hardened properties for preplaced aggregate concrete (PAC). Alkali-activated slag grouts with different alkaline activator concentration (silicate modulus and Na2O%), water-to-slag (w/s) ratio and superplasticizer dosage were produced to determine the efflux time, which is the most important fresh state property of PAC. The compressive strength of grout mixtures with appropriate fresh state properties was determined at 7, 28 and 56 days. Moreover, scanning electron microscopy and X-ray diffraction analyses were carried out to assess microstructural features of the AAS grout. The experimental results revealed that most mixtures with w/s ratio of 0.55 had appropriate efflux time. For those mixtures with appropriate efflux time, the highest mechanical strength (56 MPa) was achieved by the mixture made with 6% Na2O (by weight of slag) and silicate modulus (Ms: Na2O/SiO2) of 0.8. Results of microstructural analyses corroborated mechanical strength results. SEM suggests that mixtures with low Na2O ratio should be used to mitigate microcracks observed at high Na2O dosage. Results indicate potential to develop sustainable AAS-PAC with much less paste volume, high recycled binder content, lower energy of production, and no rheological problems associated with aggregates.

Development of sustainable preplaced aggregate concrete with alkali-activated slag grout

This study aims at endowing preplaced aggregate concrete (PAC) with exceptional sustainably via using alkali-activated grouts in its production. Accordingly, the mechanical properties and pore structure of PAC produced with alkali-activated slag grout having different alkali activator concentrations were investigated and compared to that of control OPC-based PAC. Efflux time and spread flow of the grout mixtures were determined, along with the compressive and splitting tensile strengths, modulus of elasticity, and water absorption and sorptivity of the corresponding PAC mixtures. Scanning electron microscopy and mercury intrusion porosimetry analyses were further deployed to assess microstructural features. Results demonstrate that structural alkali-activated PAC could be developed, which could offer substantial sustainability advantages in various construction applications.

Tank Drainage for an Electrically Conducting Newtonian Fluid with the use of the Bessel Function

In this study, an unsteady flow for drainage through a circular tank of an isothermal and incompressible Newtonian magnetohydrodynamic (MHD) fluid has been investigated. The series solution method is employed, and an analytical solution is obtained. Expressions for the velocity field, average velocity, flow rate, fluid depth at different times in the tank and time required for the wide-ranging drainage of the fluid (time of efflux) have been obtained. The Newtonian solution is attained by assuming σΒ02=0. The effects of various developing parameters on velocity field υz and depth of fluid H(t) are presented graphically. The time needed to drain the entire fluid and its depth are related and such relations are obtained in closed form. The effect of electromagnetic forces is analyzed. The fluid in the tank will drain gradually and it will take supplementary time for complete drainage.

Study of Electromagnetic Effect Parameters Influence on Fluidity of Fine Nd-Fe-B Powder

The paper experimentally proves the efficiency of electromagnetic effect on stimulated fluidity of magneto-hard powders. Fine Nd-Fe-B powder doesn’t have natural fluidity. To make it flow through hopper outlet we effected on the powder by constant and alternating gradient magnetic fields. Induction lines of constant magnetic field were horizontal, and alternating field lines were vertical. In order to form stimulated powder fluidity, higher induction gradient was situated below the powder receiver chamber. We experimentally found optimal magnetic fields parameters that form steady magneto fluidized bed from Nd-Fe-B powder, with an average particle size 1 μm. The study results of influence of magneto fluidized bed electromagnetic parameters on Ne-Fe-B powder efflux speed through outlets with diameters 1 and 2 mm are presented. Gradient field topology and parameters of electromagnetic effect providing minimal efflux time of 1000 mg of powder are defined.

Abdominal Massage Reduces Visceral Hypersensitivity via Regulating GDNF and PI3K/AKT Signal Pathway in a Rat Model of Irritable Bowel Syndrome.

Changes in gut motility and visceral hypersensitivity are two major features of irritable bowel syndrome (IBS). Current drug treatments are often poorly efficacious, with many side effects for patients with IBS. Complementary therapies, such as acupuncture or abdominal massage, have received more attention in recent years. In this study, a rat model of IBS with diarrhea (IBS-D) was established by instillation of acetic acid from the colon. The effects of abdominal massage on changes in gut motility, visceral hypersensitivity, and the possible mechanism were investigated. Continuous abdominal massage could decrease the stool consistency score and increase the efflux time of glass beads compared with model groups, while also decreasing mast cell counts in IBS-D rats. The mRNA and protein expressions of neuronal nitric oxide synthase (nNOS), choline acetyl transferase (CHAT), and protein gene product 9.5 (PGP9.5) were significantly upregulated by continuous abdominal massage compared with model groups. Continuous abdominal massage also improved the ultrastructure of enteric glial cells (EGCs) by decreasing the number of mitochondria and increasing the level of the heterochromatin. Meanwhile, continuous abdominal massage could upregulate the expression of glial cell line-derived neurotrophic factor (GDNF) and P-Akt/Akt. Furthermore, it could reduce visceral hypersensitivity and improve the IBS-D symptoms by regulating the phosphoinositide 3-kinase (PI3K)-Akt pathway, which would provide a novel method for the treatment of IBS-D in the clinical setting.

An Investigation of the Effects of Incorporation of Supplementary Cementitious Materials on Fresh State Properties of Grouts for Grouted Aggregate Concrete

Grout flowabiity is the key parameter in the production of grouted aggregate concrete (GAC). High flowability due to high water to binder ratio (w/b) of GAC grout in its fresh state invites bleeding and segregation whereas, low flowability due to low w/b in fresh state greatly influences setting times, loss in flowability and the grout handling process. It is difficult and crucial to have a grout that will exhibit adequate flowability in its fresh state maintaining appropriate w/b ratio. Scanty research is available in this regard and needs investigation. Therefore, an experimental study was proposed to develop the grout for GAC, investigating the effects of supplementary cementitious materials (SCMs) incorporation in place of ordinary Portland cement (OPC), for repairing or retrofitting of the reinforced cement concrete (R.C.C) piles subjected to damage or deterioration. Binary and ternary binder grout compositions, at water/binder = 0.45 and sand-to-binder ratio 1:1, using optimized poly-corboxylic ether (PCE) based high range water reducer (HRWR) adhering to the efflux time of 35-40 ± 2s according to American concrete institute (ACI) 304.1-2005, were studied to investigate the effect incorporation of SCMs, viz., fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS) and metakaolin (MK), on fresh state properties of GAC grouts. Utilization of supplementary cementitious materials (SCMs) in grouts will serve them green and will lead to ecological and economical benefits with true sustainable development. Therefore, an attempt was made to investigate the effects of SCMs on GAC grout fresh state properties for their suitability in repairs and retrofitting of R.C.C piles based on setting times, bleeding, flowability, and its loss employing flow cone method. Results have shown that grouts produced incorporating SCMs partially replacing OPC can result in many synergic effects and can offer significant benefits in view of their fresh state properties to suit with the pile repair and retrofitting methodology. Moreover, it was observed that ternary grout compositions offer significant benefits over binary grout compositions when binary grout system performing well is combined to form ternary grout system.

Ternary mix design of grout material for structural repair using statistical tools

Repair is an indispensable part of the maintenance of structures over their lifetimes. Structural grouting is a widely used remediation technique for concrete components, trenches, mine subsidence, dam joints, restoration of masonry structures, and geological stabilizations. A structural grout system should be injectable in narrow spaces and hence include ingredients with finer particles. Ultrafine cements are ideal for these type of demanding grouts due to their superior properties compared to that of the less-expensive, but coarser ordinary Portland cement (OPC). Supplementary cementitious materials (SCMs) are often used to replace OPC clinker based binder in order to modify certain properties and to reduce costs. The most commonly used SCMs are fly ash (FA), and ground granulated blast furnace slag (GGBS). For various special applications microsilica (MS), and metakaolin (MK) are also used. Identifying the optimum replacement contents of OPC by SCMs are a challenge during the design of such grouts. The aim of this experimental study is to investigate the effect of the selected SCMs (FA, MS and MK) on the slump flow, time of efflux, viscosity, shrinkage, and compressive and flexural strength of ultrafine cement based grouts with constant water-binder ratio and superplasticizer content. The test program was formulated using Box-Behnken design principles. Maximum percentages of replacement with ultrafine cement was 6% by volume of cement for MS and 16% for FA, and MK. The results suggest that most investigated grouts have the potential to be used for structural applications. The appropriate quadratic models are then formulated through statistical tools and presented as response surfaces. The trends indicate that fly ash improves the rheological properties, whereas microsilica and metakaolin positively affect shrinkage and mechanical properties to some extent. Based on the influence of SCMs and priorities among the properties, Decision Matrix Analysis (DMA) is carried out to select the most suitable ones among the SCMs. The analysis suggests that microsilica and fly ash are more suitable as SCMs than metakaolin without affecting the properties.

Factors affecting the performance characteristics of cementitious grouts for post-tensioning applications

In grouted post-tensioned (PT) systems, cementitious grouts are supposed to completely fill the interstitial spaces between the strands and act as the ‘last line defence system’ against corrosion. However, use of poor quality grout materials and grouting practices result in voided grout systems, ultimately leading to premature failure of tendons in many bridges around the world. To ensure an intact system, the grout must have excellent fresh properties, in particular the flow properties. Such high-performance grouts are not available in many developing countries, where grouting for post-tensioned structures is still a nascent technology. In this research, a two-stage test program was carried out to evaluate the fresh and hardened properties of seven commercial grouts, which includes three Pre-Packaged Grout mixes (PPG); three Site-Batched Grout mixes (SBG) and one standard Ordinary Portland Cement grout mix (PCG). Further, one PPG mix and SBG mix were chosen and their properties were evaluated for three levels of mixing speed and two ambient temperature conditions. Fresh properties such as wet density, efflux time and its retention, standard bleed, wick-induced bleed and pressure bleed, as well as set/hardened properties such as setting time, compressive strength and volume change were evaluated. Three batches of grout were tested for each grout material, to ensure reliability of results. The influence of binder fineness on the performance of grouts was also evaluated. The study serves as a strong evidence in substantiating that the most commonly used grout materials for PT system in developing countries, fail to meet the standard requirements and even the manufacturer’s own specifications. It is also found that the performance of the grout is influenced by mixing speed, ambient temperature, and fineness. The study emphasises that the evaluation of the grout behaviour under simulated field conditions is essential to ensure void free and durable PT systems.

Preparation of an amphoteric flocculant having both high polymer content and low viscosity and its polymerization kinetics

Abstract It is not easy for liquid cationic flocculant diallyldimethyl-ammonium chloride (DM) homopolymer to simultaneously exhibit both low viscosity and high polymer content, which limited its application in offshore oilfield. In this paper, sodium allylsulfonate (XS) and sodium formate were used in the aqueous solution polymerization of DM. An amphoteric flocculant (PDMXS) with the properties of high polymer content (about 55 wt%) and low viscosity (efflux time measured by an Apply 4 viscometer was less than 100 s) was prepared. The optimum reaction conditions were identified as follows: the mass ratio of XS/DM was 10 wt%, the concentration of sodium formate was 2000 mg·L− 1, reaction temperature was 55 °C, the concentration of KPS was 0.5 wt% and the reaction time was 4 h. The polymerization kinetics was discussed. The results showed that Rp ∝ [M]1.97[I]0.68[CTA]0.71 and the apparent activation energy was 72.55 kJ·mol− 1.

Densities and Viscosities for Binary Liquid Mixtures of Butan-1-ol + Propane-1,2-diol, + Butane-1,2-diol and 2-Methylpropan-1-ol + Propane-1,2-diol, + Butane-1,2-diol from 298.15 to 333.15 K at 0.1 MPa

This paper presents densities and viscosities of binary mixtures of butan-1-ol (or 2-methylpropan-1-ol) with propane-1,2-diol, and butane-1,2-diol from 298.15 to 333.15 K at 0.1 MPa over the entire concentration range. A vibrating tube densimeter provides the densities while a glass capillary viscometer provides the efflux time which is related with the kinematic viscosity. Experimental densities and viscosities of the pure components agree with data reported in the literature within an average absolute percentage deviation of 0.03% and 1.16%, respectively. The excess molar volumes and viscosity deviation calculated from experimental data present negative deviations from ideality in the entire temperature range. The Redlich–Kister equation is used to represent the composition behavior of excess molar volumes and the viscosity deviations. The Nava-Rios equation correlates our kinematic viscosity data within an overall average absolute percentage deviation of 1.085% while the McAllister equation correlates the kinematic viscosity within 1.541%.

Hydride bed control: Understanding of hydride bed using tank efflux

Control of dehydriding (desorption of hydrogen or hydrogen isotope) rate from a hydride bed in fusion fuel cycle is one important design point to estimate a real supplying amount of hydrogen from the hydride bed. In a real system tens of batch-type hydride beds are to be utilized for supplying a certain amount of hydrogen isotope at the same time. A study on efflux time from a hydraulic water tank was applied as a fundamental similarity test of the gas fueling system. As a result, liquid efflux from a tank shows a similar behavior with the desorption pattern of the depleted uranium hydride bed system. As much important as keeping a hydride buffer vessel pressure in a hydride bed system, similar tendency was studied in the tank efflux system; i.e., to keep the secondary vessel height there needs a certain amount of liquid flow from the upper tank and the tank height difference. From one tank with connected another tank flow with understanding of tank efflux model a complicated multi-tanks behavior could be understood by simulating its complex efflux characteristics, and it is likely to be applied to the multi-hydride beds system.